| secondary lymphoid tissue | <anatomy> Tissue that is particularly rich in lymphocytes (and accessory cells such as macrophages and reticular cells), particularly the lymph nodes, spleen, thymus, Peyer's patches, pharyngeal tonsils, adenoids and (in birds) the Bursa of Fabricius. Central lymphoid tissue: A term occasionally used as synonym for primary lymphoid tissue but should be avoided to prevent confusion between anatomical location, which is irrelevant and centrality in the system. Peripheral lymphoid tissue: Secondary lymphoid tissue, not necessarily located peripherally. Primary lymphoid tissue: Lymphoid tissues in which immune cells develop as opposed to the secondary or peripheral lymphoid tissues in which antigen independent or antigen dependent stages of maturation take place and in which responsive lymphocytes are found. Primary lymphoid tissues are foetal liver, adult bone marrow and thymus (and Bursa of Fabricius in birds). Secondary tissues are lymph nodes, spleen, tonsils and mucosa associated lymphoid tissue. (20 Mar 1998) |
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| hyaline degeneration of the elastic tissue of the arterial wall | Seen during involution of the uterus. (05 Mar 2000) |
| skeletal muscle tissue | <anatomy, pathology> A rather non-specific term usually applied to the striated muscle of vertebrates that is under voluntary control. The muscle fibres are syncytial and contain myofibrils, tandem arrays of sarcomeres. (18 Nov 1997) |
| smooth muscle tissue | <anatomy, pathology, physiology> Muscle tissue in vertebrates made up from long tapering cells that may be anything from 20-500m long. Smooth muscle is generally involuntary and differs from striated muscle in the much higher actin/myosin ratio, the absence of conspicuous sarcomeres and the ability to contract to a much smaller fraction of its resting length. Smooth muscle cells are found particularly in blood vessel walls, surrounding the intestine (particularly the gizzard in birds) and in the uterus. The contractile system and its control resemble those of motile tissue cells (e.g. Fibroblasts, leucocytes) and antibodies against smooth muscle myosin will cross react with myosin from tissue cells, whereas antibodies against skeletal muscle myosin will not. See: dense bodies. (18 Nov 1997) |
| nephrogenic tissue | The tissue from which the pronephros, mesonephros, and metanephros develop. (05 Mar 2000) |
| nerve tissue protein s 100 | Highly acidic calcium-binding protein found in large concentration in the brain and believed to be glial in origin; also found in other organs in the body. (12 Dec 1998) |
| nervous tissue | A highly differentiated tissue composed of nerve cells, nerve fibres, dendrites, and a supporting tissue (neuroglia). (05 Mar 2000) |
| subcutaneous tissue | The soft tissue immediately underlying the skin or epidermis. (27 Sep 1997) |
| nodal tissue | See: atrioventricular node, sinuatrial node. (05 Mar 2000) |
| dartoic tissue | Tissue resembling tunica dartos. (05 Mar 2000) |
| dermal tissue | <botany> Outer covering of plants, that includes the epidermis and periderm nonliving bark). See: dermis. (18 Nov 1997) |
| indifferent tissue | Undifferentiated, nonspecialised, embryonic tissue. (05 Mar 2000) |
| interstitial tissue | <pathology> Rather general term for mesodermally derived tissue that may be more or less specialised. Cartilage and bone are specialised connective tissue, as is blood, but the term is probably better reserved for the less specialised tissue that is rich in extracellular matrix (collagen, proteoglycan etc.) and that surrounds other more highly ordered tissues and organs. (18 Nov 1997) |
| islet tissue | <anatomy> Groups of cells found within the pancreas: A cells and B-cells secrete insulin and glucagon. See: D cells. (18 Nov 1997) |
| osseous tissue | A connective tissue, the matrix of which consists of collagen fibres and ground substance and in which are deposited calcium salts (phosphate, carbonate, and some fluoride) in the form of an apatite. Synonym: bone tissue. (05 Mar 2000) |